Grinder pump

ABSTRACT

The functions of shredding and grinding have been separated from the pumping action of the grinding pump by utilizing two separate rotor sections attached to a common driving shaft. The first rotor contains a combination shearing plate and ripping bars which provide the functions of ripping the raw material and shredding this material into a discharge cavity. The end portions of the bars more efficiently rip the raw material without second rotor section contains a pumping member in the form of an impeller which is caused to rotate in a separate pumping cavity. The impeller causes a vacuum in the discharge cavity area which pulls the shredded material into the pumping cavity for discharge.

United States Patent 1 Smith et a1.

[ GRINDER PUMP Assignee:

Filed:

Inventors: Arthur W. Smith, La Habra; Elmer Ecology Engineering andManufactu'ring, Inc., Santee, Calif.

Jan. 7, 1971 App]. No.: 104,681

[52] US. Cl. ..241/46.11, 241/257 R [51] Int. Cl ..B02c 18/40 [58] Fieldof Search ..241/46 R, 46 A, 46 B,

' 241/46.1l,46.l7, 100.5, 257G [56] References Cited UNITED STATESPATENTS 2,857,109 10/1958 Haeussler ..24l/46.l1 2,902,227 9/1959 Higer..241/257 R 3,013,736 12/1961 Pontis ..24l/46.11 2,063,996 12/1936Gervais ..241/257 R X 2,484,509 10/1949 Hopkins ..241/257 R X 1 Apr. 10,1973 2,824,702 2/1958 Lee ..241/100.5 X 2,853,249 9/1958 Wilder.........241/46.11 X 2,912,176 11/1959 J0rdan..... ..241/100.5 X 3,128,0514/1964 Smith ..24l/46.l1

Primary Examiner-Granville Y. Custer,..1r. Attorney-Albert M. Herzig etal.

[57] ABSTRACT The functions of shredding and grinding have beenseparated from the pumping action of the grinding pump by utilizing twoseparate rotor sections attached to a common driving shaft. The firstrotor contains a combination shearing plate and ripping bars whichprovide the fimctions of ripping the raw material and shredding thismaterial into a discharge cavity. The end portions of the bars moreefficiently rip the raw material without second rotor section contains apumping member in the form of an impeller which is caused to rotate in aseparate pumping cavity. The impeller causes a vacuum in the dischargecavity area which pulls the shredded material into the pumping cavityfor discharge.

6Clalms ,4DrawingFlgu' res -Fluid Flow Fig.

Fig. 3.

Arthur W. Smith,

INVENTORS.

AGENT.

Elmer J. Boggensross;

PATENTEDAFR 1 0197s I sum 2 OF 2 Arthur W. Smith,

Elmer J. Boggenstoss,

INVENTORS..

' AGENT. I

GRINDER PUMP BACKGROUND OF THE INVENTION This invention relates to apump and more particularly to a grinder pump of improved design. Pumpsof this type are normally expected to handle a fluid flow of materialcontaining all kinds of solid matter which must be collected and pumpedthrough the system. These fluids generally contain solid material suchas bone, sticks, glass, bottle caps, cans, nylon garments, rags, wood,and similar foreign matter that generally loads up and clogsconventional pumps.

The prior art discloses many patents covering the general field ofgarbage disposal grinders which operate on the principal of grinding thematerial until it is shredded and hence capable of being pumped byconventional pumping means. A significant improvement in the field ofdisposing of waste material is disclosed in the Wilder U.S. Pat. No.2,853,249 which teaches the concept of using grinding jaws for grindingthe material and in addition uses shearing edges for chopping thefibrous material into short lengths, which are readily passed into thedisposal area for conventional pumping.

The problemin these prior art devices is that fibrous material windaround the rotor shaft and eventually clog the operation of the grinderpump. The Smith U.S.

Pat. No. 3,128,051 represents still an additional concept for preventingthe grinder pump from being repeatedly clogged by the foreign material.Smith discloses specially placed orifices in the open face of theshearing plate for building up a back pressure which causes the incomingwaste material to be forced against the grinding teeth and away from therotating shaft.

The basic problems with the prior art devices however still persistssince the ripping bars not only force the waste material against thecutting rings to provide the shearing action, but must also provide thepumping action for causing the comminuted material to be discharged fromthe grinder pump. The design of the ripping bars is thereforecompromised since the propoer design for a pump is inconsistent with therequired design for the ripping action of forcing the waste against thecutting ring.

The present invention solves these aforementioned problems by this newand novel design which now allows the ripping bar to perform'thefunctions of ripping only. Hence, the end portions of the bars have apreferred shape consistent with ripping the waste and which now preventthe waste material from jamming or loading the grinder pump. The pumpingaction is now achieved by a separate pumping impeller located on aseparate rotor in a separate cavity and, hence, the pumping requirementsof the grinding pump are improved. If required, a plurality of impellersmay be used.

I SUMMARY OF THE INVENTION In this invention there is disclosed astationary housmetrical, the" entire cutting ring can be removed,

rotated and then replaced thereby providing a new cutting edge facingthe direction of the fluid flow since the shaft is arranged to rotate ina given direction. A driving shaft is located centrally within thehousing and is arranged to be driven at one end by a conventionaldriving means, such as an electrical motor. A first rotor assemblycomprising a plurality of ripping bars and a shearing plate is fixedlyattached to the shaft with the ripping bars having a reduced diameterfor rotation within the diameter of the defined cutting ring and in adirection that faces the fluid flow. The shearing plate portion has adiameter that is larger than the cutting ring and is located on the sideaway from the fluid flow and behind the cutting ring. The housingportion surrounding the shearing plate defines a discharge cavity whichaccepts the sludge that is produced by the action of the ripping barsand the shearing plate assembly. A second rotor assembly is comprised ofa pumping impeller which is fixedly attached to the shaft and is locatedwithin a pumping cavity which is defined by the enclosing housingportion. The discharge cavity communicates with the pump cavity. Thepumping action takes place solely within the pump cavity and as afunction of the rotating pump impeller. In the preferred embodiment, asingle impeller has been used. However, it is possible for large pumpingoperations to use a plurality of pumping stages each comprising aseparate impeller fixedly attached to the shaft. The total number ofimpellers will be a function of the pumping action required.

Further objects and advantages of the present invention will be mademore apparent as the description progresses.

Reference now being made to the accompanying drawings wherein;

FIG. 1 is a side evaluation of a grinder pump having a cut away portionwhich illustrates the preferred embodiment of the invention;

FIG. 2 is a section view of the pump taken along lines 2--2 of FIG.which more fully shows the combined shearing plate and ripping bar;

FIG. 3 is an enlarged perspective view-illustrating the tip portion ofthe cutting bar; and

. FIG. 4 is a front view of the pump impeller.

Referring now to FIG. 1, there is shown a preferred embodiment of thegrinder pump which includes a driving force in the form of an electricmotor 10 having an end casing 11 and a protruding shaft 12. Attached tothe end casing 11 of motor 10 is a pump and grinder portion 13consisting of an end casing 14, which is directly connected to the endcasing 11 of the motor 10 and a casing 15 which is attached to casing 14along the periphery thereof. Casings I4 and 15 define the housingencompassing the pump portion and the grinding portion of the invention.The open end of casing 15 is connected to the source of the waste fluidwhich is forced to pass through the pumping member. Depending on'theapplication, it is envisioned that either a flexible hose or permanentcoupling will connect the housing 15 to the source of the waste fluidflow. The lo'ngitudinal dimension of casing 15 will therefore be afunction only of the external coupling requirements which will connectthe pump to the external system.

The casing 15 actually defines a housing which encompasses an internaldiameter 16 through which the waste fluid passes. A cutting ring 17comprising a plurality of stacked laminations, and having an externaldiameter that is slightly larger than the internal diameter of thecasing 16 is press fit into the open end of the casing 15. A front viewof the cutting ring 17 is also shown in FIG. 2. In the preferredembodiment, the cutting ring consists of a plurality of symmetricalcutting edges 18 which are formed by a plurality of offset half circles19. The offset circles 19 on the cutting ring 17 provide the pluralityof symmetrical cutting edges 18 that do not favor either a left-hand orright hand rotation of the motor shaft 12. Practical advantages of thissystem become more evident when it is realized that the grinding shaft12 will rotate in a fixed direction throughout the normal use of thegrinder pump and, hence, only one set of edges 18 will wear out. In thepreferred embodiment casing and casing 14 are separate and are joinedtogether along the periphery thereof, and hence to replace the cuttingring 17 it is only necessary to separate the casing 14 from the casing15 without disassembling the complete grinder pump. The cutting ring 17can then be removed by a conventional pressing tool. By simply rotatingthe cutting ring 17 around a diameter and then replacing the ring backinto the casing 15 the unused cutting edge 18 will now face thedirection of the waste fluid flow. In this manner the cutting ring ismore easily removed and a new cutting edge is available without thenecessity of replacing or buying new parts.

Located on the periphery of shaft 12 is a combined shearing plate andripping bar assembly 20. The assembly 20 is either keyed or splined tothe end of the shaft 12 so as to rotate as the shaft 12 rotates. Theassembly 20 consists of a shearing plate 21 having a maximum diameter asat 22 that is greater than the internal diameter of either thecuttingring 17 or the internal casing as at 16. The minimum diameter of theshearing plate 21 is shown at 23 to have a diameter that is now lessthan the internal diameter of the cutting teeth porsociated with themoving fluid into the half circle 19 and against the cutting edges 18 ofthe cutting ring 17.

In the prior art devices the ripping bars 25 had to perform thefunctions of pumping liquid as well as the function of ripping thematerial. Hence, the design for the ripping bars 25 was compromised inorder to achieve 'a good pumping action.

The square end design presently in use which is efficient for pumping isthe primary cause forjamming and locking up of the pump mechanism. Thefibrous or bulk material being forced between the square tip of theripping bars 25 and the cutting edge 18 of the cutting ring 17 has theeffect of stalling the driving motor 10 and causing a complete shutdownof the grinding pump operation.

In this invention, stalling or lock-up of the driving motor 10 issubstantially eliminated by designing the end portion 26 of the rippingbar so as to have a rake angle with regard to the cutting edge 18 asshown in FIG. 3.

' As shown 'in FIG. 1, the waste fluid flow entersthe casing 15 throughthe reduced diameter end portion 16 and is directed to the ripping bars25 which are fixedly attached to the shearing plate 21. The defined rakeangle has the effect of pushing out or clearing any debris that may tendto jam between the face of the ripping bar 25 and the cutting ring 17.Since the pumping action is down stream of the grinding action, thefluid flow is being forced into the ripping bars 25 and the effect ofthe rake angle is to prevent debris from I jamming between the bars andthe ring but instead forces the waste back into and against thedirection of the fluid flow. This action tends to clear the area ofdebris that is not directly comminuted or otherwise forced through thecutting ring for discharge. This imtion 18 on the ring 17. In thepreferred embodiment the diameter of the shearing plate 21 is formedwith'a plurality of .cutting edges 24. The actual number of cuttingedges will be a function of the capacity of the grinder pump and thespeed of the rotation of the shaft 12.

However, in one embodiment four symmetrical cutting edges 24, eachhaving the large diameter as shown at 22, was constructed and foundsatisfactory. The purpose of the cutting edges 24 is to shear all wastematerial forced through the half circles 19 into a fluid pulp.

Attached to the shearing plate 21 and preferably by welding or similarprocess are a plurality of ripping bars 25 and preferably one for eachof the cutting edges 24 that are used on the shearing plate 23. In otherwords, if four cutting edges 24 are used on the shearing plate 21, thenfour ripping bars 25 are recommended. In the preferred embodiment theripping bars 25 are offset from the cutting edges 24 so that eachcutting edge 24 is substantially located between the ripping bars 25 asshown in FIG. 2.

In this invention as opposed to the prior art devices the ripping bars25 perform the function of moving the waste into and against the cuttingedges 18 on the cutting ring 17. There is no pumping action associatedwith the movement of the cutting bars 25 since the only purpose of thebars is to compress the waste mass asproved ripping bar can thereforeuse a smaller driving motor without fear of causing a stalling or lockupof the grinder pump due to foreign or other abrasive material beingjammed between the ripping bars 25 of the cutting ring 17.

Since all the cutting and ripping action takes place along the peripheryof the ripping bar 25, it has'been found desirable to construct theripping bar 25 with a varying thickness that is smallest at the centerwhere attachment is made to the driving shaft 12 and which graduallyflares to a maximum at the end most portion asat 26 where contact issubstantially made with the cutting ring 17. The purpose of this flaredconstruction is to continually move the waste fluid from the center lineof the pump out to the periphery where the grinding and shearing actiontakes place.

The action of the ripping bars 25 is to continuously move the wastefluid into the periphery so as to be forced against the cutting edges 18of the cutting ring 17. The continuous grinding action will eventuallycomminute the waste material until it is free to pass through the halfcircles 19. The rotating shearing plate 21 has the effect of continuallyshearing or cutting the fibrous material that passes through the halfcircles 19. In the preferred embodiment there are four cutting edges onthe shearing plate 21. In this manner all fibrous and bulk material isreduced in length to a pulp size that is capable of being pumped ormoved by conventional pumping means. i

The discharge from the half circle 19 on the cutting ring 17 will fallinto a discharge cavity 27 formed by the housing 14, which was describedpreviously as being connected at one end to the end of casing l 1 and atthe other end to casing 15. The discharge cavity 27 will be under areduced pressure caused by the pumping action to be described.

The pumping action for the Grinder Pump is a result of using an impeller28 which is attached to the shaft 12 by a spline or a key and which iscaused to rotate in a pumping cavity 29 formed within housing 14.

The impeller 28 is more fully illustrated in FIG. 4 as consisting offour blades so arranged for rotation in a preferred direction. Becauseof the separation of the grinding and the shearing action from the pumpaction, it is now possible to construct the impeller 28 withsubstantially flat ends 31 in order to take advantage of the improvedpumping action associated with this type of device. The impeller 28 maynow be constructed and fabricated of plastic rubber or other types ofresilient material as opposed to the prior art device which mustconstruct their impeller of metal since the impeller also had to servethe function of a ripping bar.

As shown in FIG. 1, the discharge from the discharge cavity 27 is alongthe center-most portion of the pumping cavity 29. Due to the action ofthe impeller 28, the pulp material is pumped centrifugally out of adischarge port 32 where the material has now been reduced to nothingmore than a slury or pulp.

Certain unobvious advantages are now possible by a direct result ofseparating the shearing and ripping actions from the pumping action. Forexample, it is now possible to add additional ripping and shearingstages between housing 14 and housing 15. Depending on the size andvolume of material to be pulverized or comminuted, it is now possible toadd a plurality of differentthickness of cutting rings 17. The firstcutting stage can be made larger than the cutting ring for the secondstage until the desired size pulp is obtained. The shearing plate forthe first stage may have only one or two cutting teeth so as to permitlonger and thicker fibers to be moved through the first stage. Thesecond cutting stage may then have a thinner cutting ring 17 and moreteeth on the shearing plate 21 so as to again reduce the size of thefibers of material passing through to the pumping member. Additionalgrinding and shearing stages would then be a function only of theexternal requirements using the grinder pump.

In view of the separate casings it is also possible to separate thecasings 11 and M and insert additional pumping stages so as to obtainthe benefits of a multiple stage pump having a plurality of impellers28. In a similar fashion therefore it isnow possible to add additionalpumping stages dictated only by the requirements of the ultimate user.

What is claimed is: I

1. A grinder pump defining a fluid flow path therethrough, comprising:

a stationary housing containing a reversible annular cutting ring havinga diameter that is less than the inside diameter of said housing, saidcutting ring having inwardly projecting cutting teeth shapedsymmetrically relative to radii therethrough; a shaft located centrallywithin said housing; a combination of ripping bars and shearing platefixedly attached to said shaft; the ripping bar portion having a reduceddiameter for rotating within the inner diameter of said cutting ring;

the shearing plate being located on the downstream side of the cuttingring and having portions of a diameter larger than said cutting ring;

the housing portion surrounding the shearing plate defining a dischargecavity, and a separate pump member fixedly attached to said shaft andlocated within a pump cavity formed by the housing and having an inletcommunicating with said discharge cavity adjacent said shaft;

the pump cavity accepting the discharge from said discharge cavity atsaid inlet and discharging or pumping the fluid flow at another point.

2. A grinder pump according to claim 1 in which said housing iscomprised of a first part defining the fluid entry section at one endand which holds the cutting ring at the other end; and

a second part defining the discharge cavity and a section of the pumpingcavity.

3. A grinder pump according to claim 1 in which each of said rippingbars has a thickness varying from a minimum at the shaft to a maximum atthe radial extremity of the bar. I

4. A' grinder pump according to claim 1 in which each of said rippingbars projects into the fluid flow a varying amount ranging from aminimum at the shaft to a maximum at the periphery of said bar.

5. A grinder pump according to claim 1 in which said cutting ring iscomprised of a plurality of identical laminations forming a stackedarray.

6. A grinder pump defining a fluid flow path therethrough, comprising:

a stationary housing having an annular cutting ring therein, saidcutting ring having inwardly projecting teeth, thereon;

combination ripping bar and shearing plate rotatably mounted in saidhousing for rotation about the axis of said cutting ring and havinggenerally radially extending ripping bars rotatable radially inwardly ofsaid cutting ring and having generally planar outer axially elongatedend edge surfaces extending generally tangent to said axis, in acircumferential direction, and arranged to define a space between saidsurfaces and the inner ends of said teeth that converges axially in thedirection of fluid flow whereby to minimize clogging of material in thespaces between said teeth.

a :r a: a

1. A grinder pump defining a fluid flow path therethrough, comprising: astationary housing containing a reversible annular cutting ring having adiameter that is less than the inside diameter of said housing, saidcutting ring having inwardly projecting cutting teeth shapedsymmetrically relative to radii therethrough; a shaft located centrallywithin said housing; a combination of ripping bars and shearing platefixedly attached to said shaft; the ripping bar portion having a reduceddiameter for rotating within the inner diameter of said cutting ring;the shearing plate being located on the downstream side of the cuttingring and having portions of a diameter larger than said cutting ring;the housing portion surrounding the shearing plate defining a dischargecavity, and a separate pump member fixedly attached to said shaft andlocated within a pump cavity formed by the housing and having an inletcommunicating with said discharge cavity adjacent said shaft; the pumpcavity accepting the discharge from said discharge cavity at said inletand discharging or pumping the fluid flow at another point.
 2. A grinderpump according to claim 1 in which said housing is comprised of a firstpart defining the fluid entry section at one end and which holds thecutting ring at the other end; and a second part defining the dischargecavity and a section of the pumping cavity.
 3. A grinder pump accordingto claim 1 in which each of said ripping bars has a thickness varyingfrom a minimum at the shaft to a maximum at the radial extremity of thebar.
 4. A grinder pump according to claim 1 in which each of saidripping bars projects into the fluid flow a varying amount ranging froma minimum at the shaft to a maximum at the periphery of said bar.
 5. Agrinder pump according to claim 1 in which said cutting ring iscomprised of a plurality of identical laminations forming a stackedarray.
 6. A grinder pump defining a fluid flow path therethrough,comprising: a stationary housing having an annular cutting ring therein,said cutting ring having inwardly projecting teeth, thereon; acombination ripping bar and shearing plate rotatably mounted in saidhousing for rotation about the axis of said cutting riNg and havinggenerally radially extending ripping bars rotatable radially inwardly ofsaid cutting ring and having generally planar outer axially elongatedend edge surfaces extending generally tangent to said axis, in acircumferential direction, and arranged to define a space between saidsurfaces and the inner ends of said teeth that converges axially in thedirection of fluid flow whereby to minimize clogging of material in thespaces between said teeth.